1. Field of the Invention
The present invention relates generally to printers, and more particularly, to a printer with image correcting capability in which difference in color tone or contrast between an image displayed on a display and an image printed by the printer is suppressed. This invention also relates to a printer that automatically corrects the tilt of a picture with respect to its frame.
2. Description of the Related Art
A number of methods have hitherto been commonly used to print pictures from natural picture data derived from photographs, digital cameras, etc. A first such method entails connecting an input device for inputting picture data to a universal computer connected to a printer. Picture data read into the computer from the input device is processed in a predetermined fashion on the computer to generate picture-printing data which is sent to the printer for printing. The input devices may be enumerated by, for example, a removable medium drive, such as a recording/reproducing apparatus for removable media; a NTSC (National Television System Committee) picture signal input substrate; a silver halide photo film scanner; or, a digital still picture camera.
A second known printing method involves directly interconnecting an input device, such as a scanner or digital still camera, to a printer without interposition of a computer. The printer is configured to receive picture data directly from the input device and to derive a picture therefrom for printing.
First Printing Method
Referring to FIG. 1, a block diagram of a system for implementing the above-noted first printing method is shown. The system is comprised mainly of a personal computer 1001, a printer 1002 and an input device 1003 Examples of input devices 1003 are as follows: a removable media drive (e.g., a disc drive for an optical disc as a CD-ROM or a rewritable magneto-optical disc as an MD-DATA disc); camcorders and the like for providing picture signals (including NTSC, PAL, RGB and S-terminal signal formats); digital still-picture cameras; scanners for silver halide photo films (35 mm film or so-called APS film having picture-related magnetic information); and original read-out scanners.
Printer 1002 employs a printer head 1004 effecting actual printing and a head driving circuit 1005 for driving the printer head 1004. Computer 1001 is mainly comprised of an interface 1006 for entering picture data from the input device 1003, a data processing unit 1007 for processing the picture data as picture-printing data, and a bi-directional printer interface 1008 for outputting the picture printing data to printer 1002. Data processing unit 1007 includes a device driver, adapted to these input devices and which is configured for controlling printer 1002, and application software designed for inputting and processing the picture data and to control the printer output. This software is configured to execute data processing via the data processing unit 1007. Computer 1001 further includes a display 1009, a command device 1010 such as a mouse or keyboard, and a picture memory 1011 (e.g., hard disc) for storage of picture data entered from the input device 1003. The input device 1003 is connected to computer interface 1006, and the computer's bidirectional printer interface 1008 is connected to printer 1002 to complete the connection.
During a printing operation, the following operations are executed. The application software for computer 1001, as well as a device driver associated with input device 1003, are activated to drive input device 1003 via interface 1006. This enables picture data to be read from input device 1003 and entered to computer 1001 via interface 1006. Based on a user command entered through command device 1010, the application software executes picture editing processing on the picture data in computer 1001. The editing may be accompanied by picture data processing performed by data processing unit 1007.
If the picture editing processing desired by the user is executed, and the picture to be printed is decided upon, the picture printing operation is commenced. Specifically, the application software controls the printer driver (which is typically implemented in software) to convert the processed picture data into printing data that can be output to printer 1002. At this time, computer 1001 determines the status of printer 1002 via bidirectional printer interface 1008.
The thus generated printing data functions as a printer control command, and is sent out via bi-directional printer interface 1008 to printer 1002. Printer 1002 then drives the print head 1004 by means of head driving circuit 1005, based on the received printing data (printer control command) to form a printed picture on a recording medium.
FIG. 2 is a block diagram illustrating a processing method as an example of data processing in the above-described operation. Slanted line segments attached to data flow lines in FIG. 2 (and in other figures herein) indicate that the data is 8 bit color data. RGB (red, green, blue) picture data input to a picture data inputting unit 1012 of computer 1001, is routed to a picture data processing unit 1013 for processing, if necessary. The picture data is stored as a picture file 1011 a in picture memory 1011 if need be. The RGB picture data is sent from the picture data processing unit 1013 to a printer driver 1014 adapted to control the printer device 1002.
Printer driver 1014, which is typically implemented in software, consists mainly of an RGB-CMY (cyan, magenta, yellow) converter 1015 for converting RGB picture data into CMY printing picture data; a color correction unit 1016 for occasionally correcting the color; a black extraction unit 1017 for extracting black hue in addition to CMY; an output gamma correction/gradation correction unit 1018 for correcting characteristics of the printer device; and a sharpness correction unit 1019 for edge processing, etc. The RGB picture data from picture data processing unit 1013 is first converted into CMY printing data by conversion unit 1015 and subjected to color correction. The color-corrected data is converted into printing data which may contain black hue. In FIG. 2, the black picture-printing data is indicated as K. The printing data is corrected for characteristics peculiar to the printer 1002, and is sent out to printer 1002 after edge processing in sharpness correction unit 1019 to sharpen the edges of objects in the pictures. If printer 1002 is embodied as a bi-level printer (e.g., inkjet) which reproduces a picture based on the presence or absence of the picture-printing dot, a convert-to-bi-level unit needs to be employed in conjunction with sharpness correction unit 1019. The convert-to-bi-level unit is unnecessary if printer 1002 is realized by a sublimation type printer that represents gradation within picture-printing dots.
Printer 1002 includes an output characteristics conversion unit 1020, the aforementioned head driving circuit 1005 and a printer head 1004. Characteristics conversion unit 1020 corrects output characteristics in accordance with the state of the printer and also suppresses fluctuations attributable to the printer. The CMY printing data sent from printer driver 1014 to printer device 1002 is sequentially forwarded via the output characteristics conversion unit 1020 to head driving circuit 1005 and to printer head 1004 for printing.
Second Printing Method
The above-noted second printing method will now be explained in detail. Referring to FIG. 3, a system for implementing this method includes a printer 1022 and a digital still picture camera 1021 operating as an input device to the printer. Camera 1021 is comprised of: a picture imaging unit 1023 for imaging an object; a command device 1024, such as a shutter, for inputting an external command; a picture memory 1025 for transient storage of an imaged picture; a picture data processing unit 1026 for effecting required data processing; and, a display 1027 for displaying an imaged picture. Printer 1022 consists mainly of an output characteristics conversion unit 1028 for correcting output characteristics in accordance with the status of the printer, a head driving circuit 1029 for driving a printer head 1030, and a printer head 1030 for effecting actual printing.
The picture data can be transferred from digital still camera 1021 to printer 1022 via a hardwire connection therebetween, or alternatively by a radio path using IR-DA or the like. The data transferred may be in the form of digital data signals or analog picture signals. To print hard copies of the picture data, the following operations are carried out. In digital still picture camera 1021, picture signals of an object generated by a picture pickup unit 1023 are provided to picture data processing unit 1026 in a state of image preparation, that is, before the user activates a shutter to start the imaging. For these picture signals, picture data processing unit 1026 performs correction processing to correct for characteristics of picture pickup unit 1023 or imaging conditions. The picture, thus corrected, is displayed on a display 1027 to permit the user to check the imaging range of the object and the background etc. If an optical finder is provided in place of or in addition to display 1027, the user can make the above check using this optical finder.
The imaging operation is initiated by the user actuating a command device 1024, such as a shutter. This causes picture data captured by picture pickup unit 1023 and corrected by picture data processing unit 1026 to be saved in picture memory 1025. Data compression may be performed on the picture data by picture data processing unit 1026 to reduce the amount of data to be stored. If the picture saved in picture memory 1025 is to be printed, the user actuates the designated command device 1024 for printing, such as a key, to start the printing operation. Picture data processing unit 1026 then reads out pre-set, compressed picture data from picture memory 1025 and occasionally expands the picture data to prepare it for outputting to printer 1022. Depending on the interfacing system for camera 1021 and printer 1022, the data is transferred as digital or analog picture signals by a radio path or over a wire. Printer 1022 converts the picture signals in the output characteristics conversion unit 1028 depending on the printing output conditions prevailing at the time of printing, and printing is effected on a recording medium by a printer head 1030 driven by a head driving circuit 1029.
The user can perform picture editing, working (e.g., adjusting brightness, contrast, etc. of an image) and synthesis processing (e.g., adding subtitles, etc.). To do this, the user inputs commands to digital still camera 1021 via the command device 1024, while checking the picture(s) displayed on display device 1027. The editing/working/synthesis processing is carried out by picture data processing unit 1026.
FIG. 4 illustrates the data processing of the second printing method. The RGB picture data obtained in picture imaging unit 1023 of camera 1021 is processed by picture data processing unit 1026 and held in picture memory 1025. The processed RGB picture data is sent from picture data processing unit 1026 via picture data outputting unit 1031 to printer 1022. Printer 1022 has, in addition to the aforementioned output characteristics conversion unit 1028, head driving circuit 1029 and printer head 1030, an application similar to the printer driver 1014 shown in FIG. 2. That is, printer 1022 includes a picture data inputting unit 1032 to which picture data is entered from camera 1021; an RGB-CMY converting unit 1033 for converting RGB picture data from input unit 1032 into CMY picture data; a color correction unit 1034 for occasionally correcting the color; a black extraction removal unit 1035 for extracting black hue (designated as “K”) in addition to CMY; an output gamma and gradation correction unit 1036 for correcting picture data in accordance with characteristics of the printer; and a sharpness correction unit 1037 for edge processing.
The RGB picture data entering input unit 1032 is first converted into CMY data and corrected for color. The picture data is then converted into printing data containing black; edge-processed, and corrected for printer characteristics of the printer. In this state, the picture data is routed to the output characteristics conversion unit 1028. If the printer is a bi-level printer, a convert-to-bi-level unit needs to be used in conjunction with sharpness correction unit 1037. If a sublimation type printer is used, the convert-to-bi-level unit is unnecessary. In any case, the CMYK picture printing data is sequentially sent via output characteristics conversion unit 1028 to head driving circuit 1029 and to printer head 1030 to effect printing.
The above-described first and second printing methods suffer from a number of drawbacks. In the first method, it is necessary to connect separate peripheral devices to a computer. The computer also needs to be equipped with disc drivers tailored to the peripheral equipment; these drivers are assembled into the computer by a laborious operation. Moreover, application software for performing processing operations such as picture inputting, picture editing, etc. needs to be installed in the computer. In a laborious operation, the application software and device drivers need to be set so that the peripheral devices will be controlled by the application software. Further, separate application software for controlling the respective peripheral devices is required. Hence, the user has to run plural application software programs and to transfer picture data therebetween, involving still more labor. Further, if a desk-top or tower type computer is used, a wide installment space is required for connecting the computer to the peripheral devices, another inconvenience.
Another limitation of the first printing method, as well as with the second printing method, is the resulting difference in the picture quality of the pictures printed by the printer and those displayed on the input device display and/or computer monitor. The main difference in picture quality is the difference in color tone and contrast between the printed and displayed pictures. In order to diminish this effect, a technique has been used in which the color tone of the displayed picture and that of a printed picture are measured with a colorimeter and these measured values are colorimetrically equated to each other. However, these measures are not fully satisfactory in that differences in color tone and contrast persist.
With the first printing method, multiple processing operations are executed by the application software on picture data. That is, the computer processor (CPU) sequentially reads out picture data from the picture memory, sequentially executes the target operation on the read-out data and re-writes the processed picture data in the picture memory. These operations are repeatedly performed. Hence, at any given time, the CPU is executing only one operation, which is not conducive to high speed processing. This problem is lessened by using a CPU which aims to increase processing speed by exploiting a pipeline structure. The parallel operation in this pipeline structure is simply the function of overlapping the consecutive process steps of the application software program just slightly by an amount corresponding to the number of pipeline steps, such that essentially the pixel data of the picture data are processed sequentially. The result is that, when executing the target processing, the larger the picture data size, the longer the time needed to complete the processing. As such, the more complex the processing contents are, the longer the time required for processing. If such processing is executed by the user with a universal computer, extra time is needed since the operator controls the start of various operations; until a particular operation is complete, the operator is kept waiting in the interim.
Depending on the processing contents, there are occasions wherein the user sequentially changes the processing parameters and checks the results to set optimum parameters. Since additional time is consumed until the processing for a sole parameter value comes to a close, it becomes difficult for an operator to compare the processing results for the respective parameters. This renders it difficult to set an optimum parameter value. This is a problem for both the first and second printing methods.
Moreover, with the first printing method it is possible to add application software for picture processing or to add certain functions to the existing application software. However, with either of these additions, since the application software for picture processing involves data communication with the above-mentioned peripheral devices, the application software or the device driver has to be re-set. Also, a device driver has to be assembled into the computer. In particular, if the application software for picture processing is universal, a variety of setting operations have to be implemented in advance. The operation methodology for this is complex, and therefore the desired processing cannot be easily performed.
In addition, in the above-mentioned software, the processing desired by an operator for a particular picture, such as editing, picture changing, synthesis, correction or printing, is executed on the basis of a specified command from the user. As such, instructions need to be issued sequentially for the picture being processed. To this end, the user has to specify the values of variable parameters for the respective processing operations. Hence, the user needs to comprehend the meaning of the variable parameters in the respective operations, as well as the degree of variation of the picture quality as a function of these parameters. The user also has to be well apprised of the method of using the application software.
In the application software, which has universal input/output functions in order to operate with common picture input devices and a majority of printer types, and which has the universal function for handling pictures at large without specifying the picture data to be handled, the method of using the application software, contents of the functions or the operating methods are difficult to comprehend, rendering it difficult for laypersons to use.
Further, the application software simply deals with the structure of the picture contents of the picture under the instructions of the user. If the user holds an image pickup device in one hand during imaging a picture such that a main portion of the resulting picture is offset or tilted to one side, the user has to correct the tilt for each picture in question. For example, if an ordinary user picks up an image of a straight road extending to the horizon or a horizontal line, as he or she holds a 35 mm silver halide film camera, there are occasions wherein the object is imaged with the camera at a tilted position due to personal habits of the user. The result is that the main portion of a picture on an imaged film is inclined with respect to the picture frame. As a result, if the object is displayed on a monitor or printed on a printer, an undesirable tilted image is produced. Although it may be possible for application software to be added to correct the tilted image, the aforementioned difficulties are present if application software is used. Therefore, with the common user not well trained in the method of operating the application software, only a tilted displayed image or a tilted print can be obtained.
As another example, if a non-expert is taking a photograph of a person using a 35 mm silver halide film camera, the usual tendency is for the face of the photographed person to be placed at the center of the finder. Thus, if the imaged picture is directly printed, the face of the person is placed at the center of the print, and the upper part of the print becomes unnecessary surrounding space. This means that it is difficult to realize a printed picture with well-balanced composition.
In the above-described second printing method, the possible processing operations such as picture inputting, editing, picture-changing/selecting, synthesis, correction or printing depend on the function of the input device, but the processing abilities of the input device are typically limited. The input device also needs to be provided with a function that allows it to be directly coupled to a printer. Moreover, the possible processing differs from one input device to another, such that the operating sequence is modified from device to device, making it non-user friendly. Also, current technology still does not permit a silver halide photo film scanner to be used as an input device with the second printing method. Further, the input device and the printer are interconnected in a one-to-one correspondence with current technology, whereby it is impossible to process and print picture data from plural input devices.
In the second printing method, since the possible processing operations such as picture inputting, editing, working, synthesis, correction or printing depend on the function of the input device, there are occasions wherein the user cannot perform the desired processing. It is also difficult to add new processing functions or to add a new function to a set of existing processing functions. Additionally, similar to the above-described first printing method, the operation of the processor (CPU) in the input device sequentially reading out picture data in the picture memory, sequentially performing the target processing on the read-out picture data and re-writing the processed picture data in the picture memory, has to be performed repeatedly, thus lengthening the time to complete the processing.
Also, with this method, it is difficult to perform the processing for arranging the picture contents in a satisfactory condition. Even if this is possible, it is up to the user to make the corrections sequentially for each picture in question.
Moreover, as in the first printing method, the input device generally does not have a picture tilt-correction function. Thus, in either of the above-described methods, it is difficult for the user to correct the offset or the tilt of the picture contents in each picture, rendering it difficult to realize a printed picture with a satisfactory orientation of the main portion of the picture.